(Epi)genetic and clinical characteristics in 84 patients with pseudohypoparathyroidism type 1B.

OBJECTIVE: Pseudohypoparathyroidism type 1B (PHP1B) caused by methylation defects of differentially methylated regions (DMRs) on the GNAS locus can be categorized into groups according to etiologies and methylation defect patterns of the DMRs. The aim of this study was to clarify the clinical characteristics of each group. DESIGN: Comprehensive molecular analyses consisting of methylation, copy number, and microsatellite analyses. METHODS: Eighty-four patients with PHP1B were included in this study. We classified them into 5 groups, namely, autosomal dominant inheritance-PHP1B (Group 1, G1), sporadic-PHP1B (G2), and atypical-PHP1B (G3-G5), based on the methylation defect patterns in 4 DMRs on the GNAS locus and etiologies and evaluated the clinical findings in each group and compared them among the groups. RESULTS: G2 had the youngest age and the highest serum intact parathyroid hormone levels among the 5 groups at the time of diagnosis. The most common symptoms at the time of diagnosis were tetany in G1, and seizures or loss of consciousness in G2. Albright's hereditary osteodystrophy and PHP-suggestive features were most frequently observed in the G2 proband. Nine patients had neurodevelopmental disorders (NDs) consisting of mild to borderline intellectual disability and/or developmental delay. There were no significant correlations between the average methylation ratios of 7 CpG sites in the GNAS-A/B:TSS-DMR and hormonal and biochemical findings. CONCLUSION: This study revealed the differences in some clinical characteristics, particularly clinical features, and ages at the time of diagnosis between G2 and other groups and detailed NDs observed in some patients with PHP1B.

Novel TRPS1 frameshift variant in tricho-rhino-phalangeal syndrome type I accompanied by zinc deficiency.

Tricho-rhino-phalangeal syndrome type I (TRPS1), caused by pathogenic variants in the transcriptional repressor GATA-binding 1 gene (TRPS1), is characterized by ectodermal and skeletal anomalies including short stature and sparse scalp hair during infancy. TRPS1 encodes a zinc finger protein transcription factor that contributes to bone homeostasis by regulating perichondral mineralization, chondrocyte proliferation, and apoptosis. Here, a male infant aged 14 months presented with sparse scalp hair, deformed nails, fused teeth, and postnatal growth retardation without neurodevelopmental disorder. As endocrinological measurements revealed low serum zinc levels, he was treated with zinc acetate hydrate, which improved his growth velocity and scalp hair. Whole-exome sequencing revealed that this patient harbored a novel pathogenic de novo heterozygous TRPS1 frameshift variant, c.2819_2822del, p.(His940Argfs*6). Zinc deficiency induces zinc finger protein dysfunction via effects on protein folding and assembly, affecting target gene transcription and apoptosis. The symptoms of TRPS1 are similar to those caused by inadequate levels of zinc, an essential trace element with important roles in tissue growth and repair. Accompanying zinc deficiency may have affected the function of important zinc finger proteins, resulting in phenotypic deterioration. Analysis of zinc metabolism in patients harboring TRPS1 variants will enhance understanding the variety of phenotypes of TRPS1.

Beckwith-Wiedemann syndrome with long QT caused by a deletion involving KCNQ1 but not KCNQ1OT1:TSS-DMR.

Beckwith-Wiedemann syndrome (BWS) is an imprinting disorder with characteristic features, such as overgrowth, macroglossia, and exomphalos. Hypomethylation of the KCNQ1OT1:TSS-differentially methylated region (DMR) on the 11p15.5 imprinted region is the most common etiology of BWS. KCNQ1 on 11p15.5 is expressed from the maternally inherited allele in most tissues, but is biparentally expressed in the heart, and maternal KCNQ1 transcription is required to establish the maternal DNA imprint in the KCNQ1OT1:TSS-DMR. Loss of function variants in KCNQ1 result in long QT syndrome type 1 (LQT1). To date, eight patients with BWS due to KCNQ1 splice variants or structural abnormalities involving KCNQ1 but not the KCNQ1OT1:TSS-DMR have been reported (KCNQ1-BWS), and four of them had LQT1. We report a Japanese boy with BWS and LQT1 presenting with extreme hypomethylation of the KCNQ1OT1:TSS-DMR caused by a de novo 215-kb deletion including KCNQ1 but not the KCNQ1OT1:TSS-DMR on the maternal allele. He was born by emergency cesarean section due to suspicion of placental abruption at 30 weeks of gestation. His birth weight and length were +1.6 SD and +1.0 SD, respectively. His placental weight was +3.9 SD, and histological examination of his placenta was consistent with mesenchymal dysplasia. He had BWS clinical features, including macroglossia, ear creases and pits, body asymmetry, and rectus abdominis muscle dehiscence, and BWS was therefore diagnosed. LQT1 was first noticed at three months in a preoperative examination for lingual frenectomy. The summarized data of our patient and the previously reported eight patients in KCNQ1-BWS showed more frequent and earlier preterm births and smaller sized birth weight in KCNQ1-BWS cases than those with BWS caused by epimutation of the KCNQ1OT1:TSS-DMR. In addition, in five of nine patients with KCNQ1-BWS, LQT1 was detected, and two of them were identified at school age. In our patient and in another single case with LQT1, the LQT1 was not detected early despite neonatal ECG monitoring. For BWS patients with extreme hypomethylation of the KCNQ1OT1:TSS-DMR, searching for CNVs involving KCNQ1 and mutation screening for KCNQ1 should be considered together with periodic ECG monitoring. (338/500 words).

Compound heterozygous variants of the NARS2 gene in siblings with developmental delay, epilepsy, and neonatal diabetes syndrome.

Neonatal diabetes mellitus (NDM) with developmental delay and epilepsy is classified as developmental delay, epilepsy, and neonatal diabetes (DEND) syndrome. The majority of DEND syndrome are due to severely damaging variants of K-ATP channels, and few mitochondria-related genes have been reported. We report here two Japanese siblings who were clinically diagnosed with DEND syndrome in whom NARS2 compound heterozygous variants were detected. Patient 1 was a 3-year-old girl and presented with diabetes ketoacidosis at 3 months old. Patient 2 was a 1-year-old boy who presented with severe hyperglycemia and started insulin therapy at 3 days old. After the first episodes, they both presented with severe developmental delay, hearing loss and treatment-resistant epilepsy accompanied by progressive brain atrophy. Whole-exome sequencing revealed compound heterozygous NARS2 p.R159C and p.L217V variants, and the GATA4 p.P407Q variant in both patients. They were treated by mitochondrial supportive therapy of vitamin B1, L-carnitine, and coenzyme Q10. Patient 2 was withdrawn from insulin therapy at 6 months old. This is the first report of NDM in which variants of the NARS2 gene coding mitochondrial protein were detected. Genetic analysis including mitochondrial genes should be considered in patients with neonatal onset diabetes associated with neurogenic symptoms.

A boy with overgrowth caused by multi-locus imprinting disturbance including hypomethylation of MEST:alt-TSS-DMR.

Most imprinting disorders (IDs) entail growth abnormalities. Some patients with IDs caused by epimutation have multi-locus imprinting disturbance (MLID) showing aberrant methylation patterns in multiple differentially methylated regions (DMRs). Patients with MLID often have typical ID-specific symptoms. However, certain MLID cases have only non-specific symptoms, and it is necessary to clarify the association between their clinical features and the affected DMRs. We report a case of MLID presenting with overgrowth and temporarily impaired glucose tolerance. Genome-wide methylation analysis for the DMRs revealed hypomethylation of PLAGL1:alt-TSS-DMR, MEST:alt-TSS-DMR, and other DMRs. Because no MEST expression and increased PLAGL1 expression cause growth failure and transient neonatal diabetes mellitus, hypomethylation of MEST:alt-TSS-DMR and PLAGL1:alt-TSS-DMR may have caused overgrowth and temporary impaired glucose tolerance in our case. In cases with multiple non-specific ID-related symptoms, such as growth abnormalities, psychomotor developmental delay, and mild glucose metabolic disorders, multi-locus methylation analysis needs to be considered.

Screening of frequent variants associated with congenital hypothyroidism: a comparison with next generation sequencing.

Congenital hypothyroidism (CH) is considered the most common congenital endocrine disorder of genetic origin. Next generation sequencing (NGS) is the standard method for identifying genetic mutations, but it is an expensive and complex technique. Therefore, we propose to use Sanger sequencing to identify selected variants of the four most common CH-causative genes: DUOX2, TG, TSHR, and PAX8. To analyze the performance of Sanger sequencing, we compared its variant detection ability with that of a CH NGS panel containing 53 genes. We performed Sanger sequencing of selected variants and panel NGS analysis of 25 Japanese patients with CH. Sanger sequencing identified nine variants in seven patients, while NGS identified 24 variants in 14 patients. Of these, eight, five, eight, two, and one were found to be potentially pathogenic in DUOX2, TSHR, TG, UBR1, and TPO genes, respectively. The percentage of detectable variants using Sanger sequencing compared with NGS was 37.5% (9/24 variants), whereas the percentage of detectable cases carrying variants using Sanger sequencing compared with NGS was 50% (7/14 patients). We proposed a system for screening commonly identified CH-related variants by Sanger sequencing. Sanger sequencing could therefore identify about a third of CH-causative variants, so is considered an effective and efficient form of pre-screening before NGS.

Incidence of childhood type 1 diabetes mellitus in Yamanashi Prefecture, Japan, 1986-2018.

Introduction: Several studies have examined the incidence of childhood T1DM in Japan from the 1970s onwards, but none have been long-term studies using registration data. We estimate the incidence of childhood type 1 diabetes mellitus (T1DM) from 1986 to 2018 in Yamanashi Prefecture, Japan. Methods: We began a population-based, long-term study of childhood T1DM in 1986 involving every hospital paediatrics department in Yamanashi Prefecture. In the Prefecture, every child newly diagnosed with T1DM is referred to a hospital, and therefore, almost 100% of new patients aged <15 years are registered. We calculated the incidence of T1DM among children aged <15 years from 1986 to 2018. All cases met the Japan Diabetes Society diagnostic criteria and were tested for T1DM-related autoantibodies whenever possible. Results: Ninety-nine patients (44 boys and 55 girls) were newly diagnosed with T1DM. The annual incidence among 5- to 9-year-olds increased by 5.35% over the study period (95% confidence interval 2.34%-8.35%, p = .0005), and there was a trend towards increasing 3-year incidence (15.52% increase, p = .0516). There were also trends towards increasing annual and 3-year incidence among 0- to 14-year-olds. However, there were no changes over time in annual or 3-year incidence in the 0-4 year or 10-14 year age groups. Conclusions: The incidence of T1DM in Yamanashi Prefecture increased among children aged 0-14 years over the study period, with the most significant increase occurring among 5- to 9-year-olds. These data suggest that the number of children aged <15 years with T1DM is gradually increasing in one of the local prefectures in Japan, Yamanashi Prefecture and that the age of onset is decreasing.